Film conveying method and apparatus



Sept. 25, 1934. L. T. TROLAND FILM CONVEYING METHOD AND APPARATUS Filed Jan. 29. 1850 er J10 atented Sept. 25, 1934 FILM CONVEYING DIETHOD AND APPARATUS Leonard T. Troland, Cambridge, Mass., assignor, by mcsne assignments, to Technicolor, Inc., New York, N. Y., a corporation of Delaware Application January 29; 1930, Serial No. 424,183

3 Claims.

This invention relates to apparatus for conveying strip material, and more particularly to damping devices for such apparatus.

Devices for conveying strip material usually 5 comprise a number of rotating rollers, wheels,

disks, or pulleys, which may be driven or undriven. The strip frictionally engages these rotating elements, resting upon their peripheral surfaces or being partly wound around these surfaces. Examples of such arrangements are conveying apparatus for motion picture film as employed in developing orprinting machines, etc. In certain instances the strip material, as for instance the motion picture film in a printing machine, does not move at uniform speed over the supporting elements as might be expected. To the contrary, quite noticeable irregularities in/ this movement take placev under certain circumstances, which cause the whole drive to oscillate and the motion of the strip material to become irregular, which is quite undesirable with such apparatus, especially if the operation of the machine in which it is employed depends to a high degree upon uniform and smooth motion of the strip, as for instance with machines working with motion picture film material.

It is therefore the main object of the present invention to provide a method permitting the smooth operation of such a conveying device at uniform speed. Other objects are to provide means making use of this method, which are simple and practically applicable to such conveying devices, which can be readily controlled and adjusted, and which will not influence the uniform progress of the strip material.

I have investigated the problems involved in the above-mentioned phenomenon and found a method. and device, constituting the present invention, which remedy the bad effect of this phenomenon. The invention will be illustrated by describing a specific embodiment thereof, which is shown in the appended drawing, in which:

Fig. i is a schematic view of a conveying device for strip material;

Fig. 2 is a velocity-time diagram of the motion of the strip material;

Fig. 3 is a side view of two adjacent pulleys connected with a damping device according to invention;

Fig. 4 is a section along line H of Fig. 3

through the damping device; and

Fig. 5 is a section along line 5-5 of Fig. 4.

Referring now to Fig. 1, 1, 2, 3, and! are pulleys supporting and conveying a film strip 5 which s'from pulley 1 to pulley 2, makes a has an absolute velocity if read from the time axis .readily understood that the relative motion besemi-circle around pulley 2, passes from there to pulley 4, and from there in similar manner over pulley 3 back to pulley 1, in a manner as described in the copending patent of John F. Kenninger, No. 1,803,115, granted April 28, 1931. The strip may either be endless or it may be fed and taken off at any-convenient point of the arrangement. One or several or none of the pulleys may be driven, the strip being drawn in the latter case through the device by external means which will thereby also rotate the pulleys.

Theoretically all of the pulleys should have the same circumferential velocity, which is also the progressing velocity of the strip and which should normally be constant, as shown by dotted line V of Fig. 2. However, due to the varying friction, the elasticity of the strip, sudden exterior impulses, the othermore or less uncontrollable iniiuences which render the connection of the pulleys 'by the strip not absolutely rigid, the speeds of the pulleys will not be uniform and they will therefore move relatively to each other. This is indicated by curve V' of Fig. 2.

Taking for instance pulleys 1 and 4, which are adjacent and connected by a rather long stretch of strip material, pulley 1 may move uniformly with speed V at which the film is supplied, whereas pulley 4-may move with a velocity 'V', which A, whereas it signifies the relative velocity between pulleys 1 and 4 if read with V as axis. In actual practice it is most probable that none of the pulleys move with the strip velocity V, but that they all oscillate out of phase to each other relative to the uniform velocity V, due to wave transmission along the strip or belt, as explained above. This relative movement between the pulleys is very undesirable; it not only imparts an undue stress to the strip and impairs the proper progress of the film, but under certain circumstances it may also cause severe oscillations which make any satisfactory operation impossible. It will be tween the pulleys is not necessarily as regular as shown in Fig. 2, that both or all pulleys may deviate from a uniform absolute speed, and that an irregular curve corresponding to V signifies the undesirable irregular relative velocity between any pair of pulleys.

In order to overcome this undesirable effect, it is necessary to eliminate the relative motion between the pulleys without influencing the uniform velocity V of the whole system. This can not be attained by braking one or several pulleys lit and eel'resp-smellng to e snrleee @l by teeteeelng their lnertlee, lteeenee tlmls would have the undesirable effect slewing detvn er etleetwlse influencing the system speed V Wltllent eecempllelene any desirable efifeet respect te the teletlve V. l eeeemplt ll tl'ie eliml= netlen ef the relative metien by e demp m lemlzlng element between pulleys having a relative metlen, fez instance pulleys l te l the present case. This element may be et any suitable eenstmetlen, eel:-

prelei' a, eenstmetlen es sllevm in t, 4, at 3 shows the entanglement et three fine leviees (l at equal inter-vale upen time at, between pulleys l end 2.

Referring n t entl t" t device tn l he sleee y el, Am r fastened upon et pulley 4 by mews el' screws 9 and lit, extension my ttve eats ll and l2 laterally tavvet 'e wheel 1. level" 13 is plvetetl ese eete by means el pin l4 entl eeerre m3 nuts lee l'l. ene end, level. l e lining l8 i steneel by enit lvle means fey e: "1113163, tlvete ptllley l. At the ether end lever l3 veslllently eenneetetl te entenslen l by means el l etelly lestenecl t0 lever with e pll: seress pertevetien 22;, lay meant at a se. between two washers all 25 entl Ln with 265 enzl 27, wlllell permit tment el tensien of eprliig It be seen that relative setween pulleys l anal is substantially e "tt etetl eemvettlng the energy causing this metlen heat the melting surface The (l ee een lee for vetlene requli'emente, es g. te tl'le lliSilC-Zlil degree at clamping, the enemy t0 lee elle slpetetl, the nature of the ee-eilletety movement between the pulleys eta, by varying; the number e1? damping devices, by elle-nelne tlie letelaing sur= face and by edjustlng the ptessilre. It will else be evident that the demplng means in newlse retards the means let elm/meme etrlp pulleys but merely etlere teemenee te vetle= tiene in veleeity between tllfiel'ent pelts et the system.

The sleeve-described embetliment of my (lamp ins eleviee is not the enly one pessllele, but e greet number at vetletiees can he eencelveel which vveultl serve the seine purpose, the gist el the invention being the mtezpesltion of an adjustable enemy eensumlng element ltetwmn conveying elements with velying relative velocity, vmtlleut efleetlng the uniletm speed with which time strip materiel eml the pulleys esppettlng it me st1p= peseel te areem-2%,

elem:

l. A film strip eenveylne eleviee comprising ttve ee=exielly meuntee." pulleys taming entl lyle= tienelly eenveylng e, length 01? film strlp e level plvetelly mounted. en ene at said pulleys and lpg a levelling sutteee, e braking surlece en the second of will pulleys, resilient means between said-level" end eeltl first pulley tending te eeltl tvve peeking" surfaces, and means fill eellust= the fierce exerted by said resilient means 2. A film eenveylng device eemprlslng mew-need, te receive etene leeetlen, elellvet the et enetllel leeatlon and, between t1 leeetlens, convey the in at least twe 3 "l5; eeme oi seltl pulleys being leeetecl l we eml etllers in another leep, and means 'lnten between pulleys ln ellfietent loops let slemp esellletiene in the film by mutual eennteree em between the in. the tespeetlve leepe eelel means eemprlslng e earned by e ptlley ln ene leep te dampen the eeelllatleps el epnlley in the other leap.

'llie metlieel el lllm which em prises cenllueting the film mung s petli. consisting of a plurality of loops, leerhng time film te leepeel petll at we lecetlen end teem the leepeel petll et mother leeetlen, and elemplng esellle-- tlens tn the leaps by lrletleeel transmission et esellletlenslmm one leap te enetllee tmpeveteely of the film se tltet the osemetiene in the respe tlve leaps tend te eeuntereet eeell other. 

